Blend the scallions, garlic, cumin, salt and pepper with 1 cup of beer.
Marinate the pork meat in the scallion marinade for at least 3 hours or overnight.
Place the onion, bell peppers and tomatoes in the food processor and process for 2 minutes.
Heat the oil in a large pot. Add the pork pieces, onion, tomatoes and pepper mixture, stir and cook for about 5 minutes.
Add the achiote, chili powder, remaining beer and bring to a boil. Reduce the heat, cover and let simmer for about 2 hours or until the pork is tender and the sauce has reduced and thickened. Add water as needed throughout the cooking process. In the last 30 minutes of cooking time, add the yuca and carrots. Sprinkle fresh cilantro and serve hot with white rice.